The invention disclosed herein pertains generally to turbo-superchargers and more particularly to an apparatus for regulating the inflow of engine exhaust gases to the turbine of a turbo-supercharger.
Due to the different operating characteristics of a combustion engine and a turbo-supercharger, it is difficult to achieve high effective mean pressures p.sub.me at reduced engine speeds. This difficulty increases with the degree of supercharging used.
The solutions hitherto proposed for overcoming this difficulty are expensive and have, therefore, not been used in the turbines of turbo-superchargers. These solutions include, for example, a turbine gas inlet housing which is constructed as a spiral, the cross-section of which spiral can be changed by means of an adjusting strap. This solution requires a not inconsiderable expenditure on structure, particularly with respect to obtaining satisfactory sealing of the strap.
An ideal solution would be a turbine with adjustable guide and rotor vanes. However, it has not yet been possible to implement a reliable and economically acceptable structure of this type.
Accordingly, a primary object of the present invention is to provide a relatively inexpensive apparatus for reliably and automatically regulating the cross-section of the turbine gas inlet at low engine speeds in order to achieve as high an efficiency as possible at low rates of flow of engine exhaust gases to the turbine.
Apparatus for regulating an inflow of engine exhaust gases to a turbine of a turbo-supercharger, according to the present invention, includes an annular diaphragm arranged within a gas inlet housing of the turbine. Connected to a lower portion of a front surface of the diaphragm is a guide vane ring. A first end of at least one spring is in contact with a back surface of the diaphragm, and a second end of the at least one spring is connected to a cover of the gas inlet housing. At relatively low engine speeds the spring biases the guide vane ring toward the gas inlet resulting in the guide vane ring filling substantially the entire gas inlet. At relatively high engine speeds, the relatively high pressures of the engine exhaust gases at the turbine inlet press the diaphragm, and the guide vane ring attached to the diaphragm, away from the turbine inlet. That is, the relatively high pressures of the exhaust gases at high engine speeds overcome the biasing force exerted by the spring.
An advantage of the present invention is that at low engine speeds the guide vanes of the guide vane ring force the engine exhaust gases to flow toward the rotor blades of the turbine at substantially the same relative angle as they flow at high engine speeds, when the diaphragm and the guide vane ring are pushed out of alignment with the turbine gas inlet. This results in a greater efficiency which enables a compressor driven by the turbine to force a greater amount of air into the engine, resulting in greater engine power at low engine speeds.